There are two kinds of luggage: hard-side luggage cases and soft-side luggage cases. Hard-side luggage cases are made by formable, hard materials, such as acrylonitrile butadiene styrene (ABS) or other materials having a generally uniform thickness, to create a protective cover for the contents of the case, thereby providing excellent stiffness and support. The advantage of the hard-side luggage cases is that they can well protect the contents of the case because they are durable and not subject to deformity. However, hard-side luggage cases have the downsides that they are typically heavier than soft-side luggage cases, that their packing space does not expand, and that external pockets are difficult to form on the outer surface of the hard-sided luggage.
On the other hand, soft-sided luggage cases have the advantages that hard-sided luggage cases do not have. Soft-sided luggage cases are relatively light-weight and their packing space can expand because they are made by using fabric layers to cover an internal frame structure. Pockets can be formed on the outer surface of the soft-sided luggage cases. However, soft-sided luggage cases do not provide secure protection of the contents therein and contents may be damaged.
To overcome the downsides of the hard-sided and soft-sided luggage cases, hybrid luggage cases have been introduced and developed by combining hard-sided and soft-sided luggage structures. Hybrid luggage cases typically have hard-sided portion and soft-sided portion which are attached to each other by sewing or other type of mechanical fastening. Hybrid luggage cases can provide a secure protection of the contents and the packing space can expand toward the direction of the soft-sided portion.
However, hard-sided portion of the hybrid luggage cases does not typically have sloping curved edges because in manufacturing them by injection molding, mold cannot be removed if there are sloping curved corners. If the hybrid luggage cases have sloping curved corners, contents can be more securely contained in the case as they do not fall out.
Therefore, to solve the above problems, a need for a luggage having an integrated structure with sloping curved corners and its manufacturing method has been present for a long time considering the expansive demands in the everyday life. This invention is directed to solve these problems and satisfy the long-felt need.